Pneumatic tool.



No. 800,329. PATENTBDSEPT. 26, 1905.

J. A. SHEPARD." PNEUMATIG TOOL. APPLICATION FILED DIEU.3, 1902.

2 SHEETS-SHEET 1.

WITNESSES:

ton, the exhaust-passages from the front end hereinafter and more,NITEDJ fsfrnirns PATENT OFFICE.

JAMES A. SHEPARD, OF MONTOUR FALLS, NEW YORK, ASSIGNOR TOTHEGENERAL'PNEUMATIO TOOL COMPANY, OF MONTOUR FALLS,

NEW YORK.

PNEUMATIC Tool..

Patented Sept. 26, 1905.

Application filed December 3, 1902. Serial No. l3 3,'75l0.

To all whom t may concern/.-

reciprocation of the piston being governed by van automatic valve theshifting'of which is controlled by the piston.

The object of my improvements is to so construct and arrange theadmission and exhaust ports and passages and the automatic valve thatthe piston may be thrown forward with the full pressure of the live airupon-,it` and with a free exhaust from infront of thev pisof thecylinder being of such number and capacity as to permit of the passageof the Iair from infront of the piston without the least back pressure,to so arrange the said ports and passages that the piston will bereturned with a slower stroke, and to so time the shifting of the valveas to cutoff the exhaust and admit air to the rear of the piston beforeit reaches the end of its rearward stroke in order to provide a cushionto prevent shock at this end of the piston-stroke. This and other novelfeatures in the construction of my hammer will be fully describedparticularly pointed out in the claims. l

I attain my object by means of the construction and arrangement of theseveral parts of the hammer, as illustrated in the accompanyingdrawings, in whichl Figure 1 represents a transverse section of thehammer on linell in Fig. 5; Fig. 2, asimilar section on line 22 in Fig.5;` Fig. 3, asect-ion on line 3 3 in Fig. 5; Fig. 4, a detail showing asection of the valve-box removed; Fig. 5, a plan View of the outer faceof said valvebox; Fig. 6, a detail showing a transverse section of thevalve, "and Figs. 7 and 8 details showing myimproved locking devicebywhich theI parts of the hammer are secured together.

i throttle-valve. .boxis provided with four annular grooves,

Like characers of reference designate like parts in the several views.

A represents the barrel orcylinder of the tool, and B thev handle, theseparts beingl united by meansof the coupling-sleeve O, which is screwedinto the handle B, as indiicated. f In order" to hold these parts fromjarring loose when the tool is in operation, l

provide the outer rim of the handle B with lserrations, as shown in Fig.7 andinthe externall shoulder or liange on sleeve O in an inclined notchcut therein with slightlydove` ltailed sides is inserted a dog orlockingblo'ck D, provided with serrations to cor- Lrespond with those onvthe rim of handle B. ,Inl assembling the parts after the sleeve O isvIset up tight .in handle B'the block D is in# serted, after which thesleeve O is given a slight backward turn to bring the teeth on I`block Dinto close engagement with those on- .handle B. The block is then heldin place by ereason of theangle which its sides make with the horizontalfaces of the teeth on handle B, and' it cannot be removed except byforcing.V the sleeve forward again to release the teeth.

Within the ,chamber formed between the endfof cylinder A andthe handle Bis an annularvvalve-box E, the bore ofwhich is in axial alinement withthat of the cylinder. This' valve-box is of smaller external diameterthan3 the insideV diameters of. the sleeve O- and the handle B at thisIpoint, thereby forming an annu1ai--exhaustchamber F all around thevalve-box, from which the exhaust-air passes: by way of port d. Fastenedbetween the rear' face of valve-box E and the end of the cham-A ber F inhandle B is a cap G, which fits over and around the cylindricalprojection I at the rear of the valve-box, thereby forming two chambers-J and K, in thelatter'of which' reciprocates the enlarged head of thevalve L. Surrounding cap Glin handle B is a'chambery H, intowhich leadsthe air-supply from the The inner wall of the valvewhich willhereinafter be designatedjas grooves l, 2, 3, and 4, beginning at theouter end of` the valve-box, as` indicated'in Fig." Hand the valve L isprovided Awith/a groove Zof 'ajwidtlrY `suficientto placetwo'of thegrooves in the:

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valve-box into communicationjwithonefanJ vIo other. This valve L ishollow and is provided with a series of holes or small ports at fr ands. (See Fig. 6.)

M is the piston, which is grooved at m for a purpose hereinafter toappear. rl `he end of the piston is provided with an annular bore P toreceive the sleeve O, which projects from the block N, which closes theouter end of cylinder A. By this construction air will be trappedbetween the end of the piston and the block when the shank Q of aworking tool is not in place in said block or has been thrown out to theextent of its stroke by the hammer In order that the shank Q, may beretained in block N when manipulating the hammer, l provide a split ringR in groove a, this ring after being sprung into said groove projectinginwardly,so as to engage the groove g in shank Q, this groove q beingmade of sufficient width to allow for the vibrations or reciprocationsof the tool when struck by the piston. It will be understood that thegroove n is of sufiicient diameter to allow for the spreading apart ofthe ring R when the shank Q, is forced into or out of the block N wheninserting or removing it from the hammer.

I have shown the ring R and the groove n of such size that the ring Rwill be principally contained in the groove n, so that when the shank Q,of the working tool is withdrawn the ring R will be retained in thegroove n. Also the groove n is shown in the bushing N. Obviously thegroove n may be cut directly into the wall of the cylinder where a`bushing is not used to form the end of the cylinder. Also the groove nmay be made shallow, while the groove g in the shank of the working toolQ may be made deeper, so that the ring R will be retained in the grooveq. I do not, therefore, limit my invention to the precise arrangementshown in the drawings, but desire to cover, broadly, the use ot' theelastic ring and any arrangement of grooves suitable for a tool of lthetype described.

Referring next to the ports and passages by which air is admitted to andexhausted from the cylinder and the valve-box, Fig. 5 represents a planview of either the outer face of the valve-box E or the inner face orend of cylinder A and shows the number and location of the severallongitudinal passages in the valve-box and cylinder-walls leading fromthe cylinder to the grooves and chambers in and around the valve-box.rl`he admission-passages leading from chamber H to groove Z in valve-boxE are indicated by a, there being four of these passages, as shown inFig. 5. From groove 4 passages lead to ports near the outer end of thecylinder, these ports being in line with the inner end of sleeve O. (SeeFigs. l and There are four of these passages ,and they are of largerdiameter than any of the other passages in order that the exhaust may befree from the outer end of the cylinder. From the inner end of thecylinder passages e lead to groove Q in the valvebox, and from groove 3radial passages w lead out into exhaust-chamber F. 'lhere are l'our ofthese passages c, preferably ol slightly smaller diameter than passageso.

Referring to Fig. 2, wherein are shown the ports and passages foroperating` valve li, f

indicates a passage running from chamber .l to the two ports .r/ and t,positioned as `shown, and vf is a passage leading' from chamber l( to aport slightly in advance of port /1f. From the port in line with port /ta passagej, (indicated in broken lines in Fig. 2,) leads to one of theexhaust-passages c. From the chamber l( a restricted passage /if (secFig. 3) leads to exhaust-chamber F, by which the outer end of thischamber K is always open to the exhaust.

Having thus pointed out thc locations ol the different ports andpassages, the operation of the tool will be understood as follows: Withthe valve and piston in the positions shown in Figs. l and 2 the airwill pass from chamber H through passages a and groove l in thevalve-box to the rear of the piston, throwing the piston outward withthe full force of the air. The air from in 'frontol the piston isexhausted by way of passages I), grooves 4 and 3 in the valve-box, andpassages c into the exhaust-chamber F, whence it passes out through port(Z, the grooves 4. and 3 being placed in communication during thisperiod by groove Z on the valve. As the pasges ZJ are large and numerousand the passage from the groove 4 to groove 3 around the valve is ofcorresponding area, the air will be exhausted from in front of thepiston without back pressure and the full force of the live air-pressurewill be expended upon the piston in delivering the blow at the end olthe piston-stroke.

Referring to Figs. Z and 3, when the rear end of the piston on itsoutward stroke has passed port g the live air from the supply will passinto passage f and thence to chamber J, where it will act upon theenlarged head of the valve to throw the valve outward into position forthe return stroke of the piston. The air from in front o1 this enlargedhead of the valve in chamber l( passes out through the small passageinto exhaustchamber F. As soon as the valve is shifted into the positionshown in Fig. 3 the live air from passages aand groove 1 will passthrough the ports r into the interior of the valve and thence throughthe ports s to groove Ll and passages which carry it to the front end ofthe cylinder to throw the piston to the rear. During this rearwardstroke of the piston the air is exhausted by way of passages 1 andgrooves 2 and 3, which are now in communication by way of groove l onthe valve to the passages c, leading to exhaust-chamber F. ln order thatthe force of the air for the return stroke may be reduced so as to givea slower return movement to the piston, ports r and s IOO IOS

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'sus

in the valve are restricted infarea, and Y.the

exhaust-passages e are also made smaller in diameter than the passagesb. i i' Reducing the capacity of the passages 'e also .insures at alltimes some pressure at the rear -properly restrain the exhaust from therear of the piston I make those portions of the passages e which are inthe wall of the cylinder smaller in diameter andthe passages less innumber than the portions of said passages which are in the valve-block.Bythis means a valve-block having ports e of suicient capacity toproperly exhaust the air from the rear of a piston having a long strokewhen used with a barrel of extremely short stroke will be properlymodified in its action to suit Vthe needs of the shorter stroke, andperfect interchangeability of these partsin hammers o f all sizes isthus secured. LOne handle with a standard valve-block and valve maytherefore be applied to cylinders of different strokes, and the numberof standard parts for the purpose of interchangeability will be reducedto a minimum, resulting not only in economy in manufacture, but also inconvenience in use.

Just before thepiston reaches the position shown in Fig. 2 passages fand j' will-be placed in communication by wayof port t and the groove mon the piston, thereby opening the chamber J to the exhaust,- since thepassage j leads into one of the exhaust-passages 0, and as soon as theforward end of the piston has uncovered the port leading-to passage t'the liveair vwill Apass therethrough to the chamber K in front of theenlarged head of the valve L, thereby throwing the valve to the rear andclosing off the exhaust from passages e and admitting air throughpassages t to throw the piston forward again.A As this shifting of thevalve and the cutting off of the exhaustthrough passages e takes placebefore As the chamber K is open to the exhaust' at all times through therestricted passage-Za, the air after being admitted through passage z'to throw the valve to the rear will slowly escape through thesaidpassage la; but the valve will stillbe held firmly seated in itsrear-A ward position by reason of the live air which is now admitted tothe cylinder between vthe forward face of the valve and the piston.'V Itwilltherefore ber'readilyunderstood that no Y iiuttering of the valvecan take place at either stroke, since the valve will be held firmlyseated by. the pressure either of the live air admitted between it andthe piston'as soon as, it has been shifted to the rear or of the airbehind it in chamberJ when the valve is in its forward position, the airfrom chamber K at this time having been exhausted throughI the passagela and the air in chamber J being trapped' therein during the returnstroke of. the piston until the port has been placedfin communicationwith the exhaust-passage j by way of the groove m 'on the piston. Itwill be noted that there are three differential areas on the Valve L,the forward` face `of the valve being exposed directly to the ad- `ofthe piston when the port g is uncovered tov force the valve forwardagainst the air-pressure in the cylinder, and the intermediate annularface at the forward side of the enlarged head of the valve, which isalways exposed to vthe exhaust byway of restricted passage 7c vandintermittently exposed to the pressure of the air passing from. the.forward end of the` cylinder through passage t' when the piston isapproaching the end of its rearward stroke.

Moreover, the valve when shiftingk travels inV the same direction inwhichvthe piston is moving. From an inspection of Figs. 1. to 5 it willbe seen that by reason ofthe axial. alinement of` roo the valve-box withthe cylinder and the.

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inder at full pressureto drive the piston forwardand with reducedpressure atthe frontf end of the cylinder for the return stroke ofthepiston. In Fig. 5 I have shown four admission-passages a inthevvalve-box, four large passages 'b leading therefrom to the forward' endof the cylinder, and .four passages of intermediate size e for theexhaust from the rear end of the cylinder. Passages fdl, and j, whichare utilized for shifting the valve, are of still smaller. diameter, asveryllittle air is required forI this purpose. p' p indicate sockets,for dowel-pins, by which` thevalvebox and cylinder. arejfastenedtogether in proper alinement. It will be eyident that by varying the.size and number/of the passages a, b, and e I may'attain Aany desiredregulation in the, speed of. the piston travel in either. direction.

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On the outward stroke of the piston after the blow has been deliveredand the forward end of the piston has closed the ports into passages bthe air in front of the piston and between it and block N will becompressed by reason of the sleeve O and groove P, already referred to,so as to prevent a blow from the piston upon block N, and this provisionfor cushioning the forward end of the piston will also prevent a blowupon said block N when the shank of a tool is not in place within thesocket.

I am aware that valved pneumatic hammers have been constructed withports of diderent capacity, whereby the movement of the piston in onedirection will be more rapid than in the opposite direction. Heretoforethis has been accomplished by contracting the admission-ports, and isopen to the objection that the piston is controlled by air under onlyslight pressure and the speed at which the piston makes its rearwardstroke will be much more influenced by the amount of rebound from theworking tool than by the quantity of air delivered through the ports.This is particularly noticeable when the hammer is used for drivingrivets and also when the direction of the blow is upward. Vhile therivet is soft and yields readily there will be very little rebound and acomparatively slow return of the piston. As the rivet cools the reboundincreases, greatly increasing the velocity with which the pistonreturns, and consequently the number of blows struck in a given periodand the recoil of the hammer. I have found in some cases that therebound will cause a pressure beneath the piston less than atmosphericpressure. By my improvement the velocity of the rearward stroke islargely controlled by the exhaust from behind the piston, since thepiston cannot return except against a heavy pressure until the pe riodnecessary to exhaust the air behind it has elapsed. rIhe speed istherefore very nearly uniform under all conditions and is not sensiblyaffected by the position of the hammer or the amount of rebound. I donot claim, broadly, the use of ports of differing capacity leading tothe respective ends of the cylinder; but the scope of my invention isrestricted to the use of exhaust-ports of differing capacity in a valvedhammer leading i' rom the respective ends of the cylinder and means forvarying the exhaust function of the valve by varying the construction ofthe cylinders only.

Having thus described my improvements and pointed out the particularfeatures which I deem to be novel and important, what I claim as myinvention, and desire to secure by Letters Patent, is-

1. In an impact-tool, the combination of a cylinder, a reciprocatingpiston therein, and avalve to control the movements of the piston, saidvalve having differential pressure areas,

of which one of the smaller areas is constantly exposed to theintermittent pressure ol the motive fluid in the cylinder acting on oneside of the piston, the greater area being intermittently exposed to thepressure of the niotive fluid acting upon the same side of the piston,and au intermediate area being intermittently exposed to the pressure oithe motive iiuid acting upon the opposite side ol the piston.

2. In an impact-tool, the combination of a cylinder, a reciprocatingpiston therein, and a valve to control the movements of the piston, saidvalve having differential pressure areas, of which one of the smallerareas is constantly exposed to the intermittent pressure of the motivefiuid in the cylinder acting on one side of the piston, the greater areabeing intermittently exposed to the pressure of the motive iuid actingupon the same side of the piston, and an intermediate area beingintermittently exposed to the pressure of the motive iiuid acting uponthe opposite side ofthe piston, the admission to said 4last two areasbeing controlled by the piston through passages leading thereto from thecylinder.

3. In an impact-tool, the combination oi a cylinder, a reciprocatingpiston therein, and avalve to control the movements of the piston, saidvalve having differential pressure areas, of which one of the smallerareas is constantly exposed to the intermittent pressure of the motiveiiuid in the cylinder acting upon one side of the piston, the greaterarea heilig intermittently exposed to the pressure of the niotive iiuidacting upon the saine side of the piston, the admission and exhaust toand from said area taking place through passages controlled by thepiston, and a third and intermediate area being intermittently exposedto the pressure of the motive Huid acting upon the opposite side of thepiston, admission to this last area being by way of a passage controlledby the piston, and exhaust therefrom being open at all times through acontracted passage.

4. In an impact-tool, the combination of a cylinder, a reciprocatingpiston therein, a valve-box in axial alinement therewith, adifferentialpistonvalve therein, the forward face of which controls the admission ofmotive fluid to the cylinder at the rear of the piston and is constantlyexposed to the intermittent pressure of the motive fluid on that side ofthe piston, the rear face of said valve being of larger area andintermittently exposed to the pressure of the motive iiuid acting uponthe same side of the piston and to the exhaust by way of passagescontrolled by the piston, an intermediate face on said valve beingintermittently exposed to the pressure of the motive fluid acting uponthe forward end of the piston by way of a passage opened by the pistonduring its rearward stroke, exhaust from said face being open at alltimes through IOO IOS

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a contracted passage, and ports and passages leading to and from theends of the cylinder controlled said valv-e. y

5. In an impact-tool, the combination of a cylinder, a reciprocatingpiston" therein, a

grooved valve-.box in axial alinement therewith, a cylindrical extensionofA larger ,bore at the rear of the valve-box, a cap-piece surroundingsaid `e'xtenslon and separatlng it -from the source of motive-fluidsupply, a

grooved piston-valve having an enlargedhead 4reciprocating in thevalve-box and its extension, passages leading from each side of the ivalve-head to the cylinder whereby admission and exhaust vof the motivefluid to and from the opposite faces of said head are controlled by thepiston, portsand passages leading from the ends of the cylinder togrooves in the head to the cylinder and the exhaust-outlet wherebyadmission and exhaust of the motive iuid to and from said chambers arecontrolled by the piston, the first groove in the valvebox nextl the`cylinder being connected with the source of Huid-su pply and beingopened directly to the cylinder when the valve is retracted, thesecondand fourth grooves in the valve-box being connected by passages with thecylinder at its rear and forward ends respectively, and the third groovebeing connected with the exhaust-outlet, ports in the valve'whereby thefirst and fourth grooves are placed in communication through the valvewhen in its forward position, and a groove on the valve whereby thesecond and fourth grooves are placed in alternate communication withthethird groove.

7. In an impact-tool, the combination of a cylinder, a reciprocatingpiston therein, a valve-box havingagrooved bore in axial alinementtherewith, a plurality of passages of comparatively large diametervleading to one of said grooves from one end of the cylinder,

I .one or more passages of smaller capacity leading from the other endofthe cylinder to another of said grooves, admissionand exhaust v passagesleading to and from other of said grooves, and a valve to control theintercommunication 'of said grooves shifted by the motive iuid actingupon the valve through passages controlled by the piston, the motivefluid being admitted directly to the cylinder for one'stroke of thepiston and by wayof; l

contracted ports'leading through a chamber in the valve for the returnstroke.

8. In an impact-tool, the combination of a cylinder, a reciprocatingpiston thereingzports and passages of different capacity leading to"avalve-chamber from opposite ends of the cylinder, a valve in saidchamber whereby the `motive fluid is admitteddirectly to one endgof thecylinder and indirectly through contracted passages to the other end,the passages from'-I the' two ends of the cylinder being placed bythevalve in alternate communication with a common exhaust-outlenwherebythe piston may be moved at high velo'city and without back pressure ,inone direction and at a slower and restrained speed in theoppositedirection.

9. Inan impact-tool, the combination of a Cylinder, `a pistonreciprocating therein, -a valve-chamber, one or more passages leadingfrom a source of fluid-supply to a circumferential port or row of portsin the valve-chamber, and a valve in said chamber whereby said port orports are uncovered to admit the motive iiuid directly to one side vofthe piston when the valve is moved in one direction,` and whereby saidport or ports are placed in communication with the other side of thepiston by way of a port or ports leading to a chamber within the valveand thence by ports and passages to thecylinder when the valve is movedto its other position.

10. In an impact-tool, the combination ofv a cylinder, a pistonreciprocating therein, a valve-chamber provided with a ser1es ofc1rcumferentlal grooves or ports, passages leading'therefrom to thesource of motive supply,

to the exhaust-outlet, and `to the cylinder at each sideof the piston,and a hollow grooved valve reciprocating in said chamber, wherebylcertain of the grooves or ports in the chamber are placed inintercommunication through ports leading to and from the interior of thevalve, and others of said groovesv or ports are placed inintercommunication by the groove IOO IIO

on the valve, as the valve is shifted from one position to the other.

11. In an impact-tool, the combination with I thecylinder, piston andcontrolling-valve, of a block or bushing'closing the outer end of thecylinder and adapted to receive the shank of the working tool, a sleeveprojecting into the cylinder from said block, an annular bore in theendof the piston to fit said sleeve, and a port or ports in saidcylinder at or near the inner extremity of said sleeve leading to thechamber of the controlling-valve, as and for the purpose set forth.

12. In a tool of the type described, the combination, with the barreland handle, of a coupling-sleeve having an external flange with a notchor recess running across its outside periphery, a locking block or dogfitted in s aid recess and provided with serrations adapted to bebrought into engagement with correspending serrations on the rim of thehandle when the parts are assembled.

13. In a tool of the type described, the combination, with the barreland handle, ot' a coupling-sleevehaving an external flange With a notchor recess running across its outside periphery, a locking block or dogfitted in said recess and provided with serrations, the contact-faces ofwhich are set at an incline to the guiding sides of the notch or recess,and co1'- responding teeth on the rim of the handle to be engagedthereby when the parts are assembled.

14. In a tool of the type described, alocliing device for thescrew-coupling whereby the handle and cylinder are united comprising lablock or dog movably mounted in a socket or recess in one member of thecoupling and provided with .serrations adapted to engage correspondingserrations upon the other member, the interlocking faces of saidserrations Where they come into contact being set at an angle to theguiding sides of said socket in opposition to the line of Withdrawal ofthe locking-block, whereby the coupling members must be set up tighterby a partial rotation in order to release said block.

15. In an impact-tool, the combination of a cylinder, a reciprocating'piston therein, a valve to control said piston operated byfluidpressure, a passage or passages or comparatively large capacityleading' from the lorward end of the cylinder to the valve and thence tothe exhaust, a passage or passages ol less eapaeity leading from therearward end ol the cylinder to the valve and thence to the exhaust,wheeby the piston may he moved at high velocity and with slight backpressure toward the working tool and at a slower and restrained speedagainst hack pressure away from the working tool, an appreciablepressure being maintained at all times at the rear of the piston.

In testimony whereoil I have al'lixed my signature in presence of twowitnesses.

JAMES A. SHEPARD.

I/Vitnesses:

Jos. VVoLvERToN, W. H. SHEPARD.

